The present exemplary embodiment relates to the detection and transport of small particles. It finds particular application in conjunction with the scientific instrumentation arts, and will be described with particular reference thereto. However, it is to be appreciated that the present exemplary embodiment is also amenable to other like applications.
In many analytical and instrumentation environments it is necessary to detect or obtain measurements of particles that are dispersed throughout a liquid or gas medium. This can be very difficult if not impossible if the particles are at relatively low concentration levels in the medium. This phenomenon can also occur when attempting to detect or measure liquid droplets dispersed throughout a gas medium. Accordingly, there is a need for a system and method to enable or at least improve the detection or measurement of particles or droplets of liquid in a medium.
It is known to utilize a tapered duct or narrowed flow channel to promote detection or measurement of particles in a flowing stream. However, a mere tapering or constriction in the flow channel is undesirable in that such geometry results in an increased flow impedance. In addition, such tapering or other geometry change does not change the relative concentrations of particles in the flow stream.
Particles can be manipulated by subjecting them to traveling electric fields. Such traveling fields are produced by applying appropriate voltages to microelectrode arrays of suitable design. Traveling electric fields are generated by applying voltages of suitable frequency and phases to the electrodes.
Although a wide array of particle transport systems are known, including those that use traveling electric fields, a need remains for strategies and systems that are particularly adapted for selectively transporting particles over certain paths, or in a certain manner; systems that can be readily implemented and used with currently available instrumentation; and systems of relatively small size that can be used to selectively transport and/or mix multiple populations of particles. Specifically, a need remains for improved transport systems that can be readily utilized in conjunction with analytical instruments.